Fluid motor



y 1963 P. M. STUVER 3,090,363

FLUID MOTOR Filed July 18, 1961 2 Sheets-Sheet 1 IN VEN TOR.

PQUL M- 5 TUVEQ ATTORNEY May 21, 1963 P. M. STUVER 3,090,363

FLUID MOTOR Filed July 18, 1961 2 Sheets-Sheet 2 INVENTOR. Pm/L M, S TU E ATTORNEY United States Patent 3,090,363 FLUID MOTOR Paul M. tuver, 1625 W. Pico, Santa Monica, Calif. Filed duty 18, 1961, Ser. No. 124,990 6 Claims. (Cl. 121121) This invention relates to a reciprocating piston driven fluid pressure operated motor and more particularly to such a motor having cylinders radially disposed about a common drive shaft.

The prior art contains many references to fluid operated motors. Most, if not all of these are subject to several major criticisms. These motors generally employ highly complicated ducting and valving systems for distributing the fluid between the pressure source and the individual cylinders. Because of their complexity these inventions are expensive to build and maintain, and commonly are subject to breakdown during operation. As a rule, the more intricate these systems are, the less efl'icient the motor. And many of the existing motors are inherently too inefiicient for satisfactory commercial use.

It is the prime object of this invention to provide a new and novel design for a fluid motor which is not susceptible of these criticisms.

A principal object of the invention is to provide a reciprocating piston driven fluid pressure operated motor in which the forces exerted by the fluid upon a plurality of pistons are transmitted directly to a single centrally located drive shaft thereby eliminating the need for a multiplicity of complex and ineflicient driving linkages.

Another object is to provide for use in connection with fluid operated motors a simple, compact, eflicient, and relatively trouble-free rotary fluid control valve assembly capable of receiving, metering, distributing, are-collecting, and discharging fluid under pressure in all stages of which the rate, course, and direction of flow of the fluid remain substantially uniform.

A further object is to design a fluid operated motor having a single centrally located rotary valve directing and controlling the flow of the driving fluid to each of a plurality of cylinders and capable of readily reversing the direction of flow of the driving fluid to provide positive braking action or to reverse the direction of rotation of the motor.

Another object of this invention is to provide a reciprocating piston driven fluid operated motor in which a single passage within the body of each cylinder is utilized for both intake and discharge of the operating fluid.

Still another object is to provide a reciprocating piston driven fluid operated motor having a plurality of cylinders integrally mounted on and disposed radially about a central crank case with each cylinder displaced ahead of or behind the preceding one suificiently to permit the connecting rods within the cylinders to lie along the center lines of the cylinders.

It is a further object to provide .a motor having the characteristics heretofore described which may employ either hydraulic or pneumatic means to furnish the operating fluid pressure. It is likewise an object to design such a motor which is capable of being operated efficiently with relatively low fluid pres-sure (e.g. up to 1500 pounds per square inch) and at relatively slow rotational speeds (e.g. up to 1000 revolutions .per minute).

Another object is to provide a highly eflicient fiuid operated motor of simple, compact, and sturdy design capable of being manufactured inexpensively and operated economically and requiring a minimum of maintenance and repair.

In its broadest sense the invention comprises one or Patented May 21, 1963 more cylinders each having within it a reciprocating piston, a single fluid intake and discharge passage for each cylinder communicating with the work chamber of the cylinder at one end and with a fluid pressure source and fluid exhaust means at the other end, operative means connecting said piston or pistons with a drive shaft, and valve means adapted to utilize the rotary motion of said drive shaft to control the sequence of distribution of fluid to and discharge of fluid from each cylinder.

Throughout the specification and claims the term uid is used to connote both liquid and gaseous substances, since the invention will operate efliciently using either a hydraulic or pneumatic pressure source.

In addition to those set forth herein, the invention comprises many other novel details of construction and combinations and arrangements of parts, and all of these, as well as other and further objects of the invention will be apparent to those skilled in the art from a reading of the following specification and by reference to the accompanying drawings. It must be made clear at the outset that the specification and drawings illustrating the preferred three cylinder form of the invention relate to but one embodiment of the invention, and are not intended to limit the scope of the invention.

In the accompanying drawings:

FIGURE 1 is a perspective view, of a three cylinder fluid motor assembly according to the invention, showing in schematic form the relationship between the motor, its pressure fl-uid source and fluid reservoir, and the valve means for controlling the direction and rate of flow of the operating fluid.

FIGURE 2 is a front vertical sectional view of said three cylinder fluid motor assembly taken on the line 22 of FIGURE 3.

FIGURE 3 is a side vertical sectional view of said three cylinder fluid motor assembly taken on the line 33 of FIGURE 7.

FIGURE 4 is a fragmentary horizontal sectional detail of the valve system of said three cylinder fluid motor assembly taken on the line 4-4 of FIGURE 3.

FIGURE 5 is a vertical sectional detail of the same valve system taken on the line 55 of FIGURE 3.

FIGURE 6 is a vertical sectional detail of the same valve system taken on the line 66 of FIGURE 3.

FIGURE 7 is a fragmentary view of the said three cylinder fluid motor assembly showing the displacement of the cylinders longitudinal of the crank case.

Referring now in detail to the drawings, the numerals 11, 12 and 13 indicate the three cylinders of this form of the invention. Preferably the cylinders are cast integral with the motor block 14. Because of its excellent strength-to-weight and heat-dissipating characteristics, aluminum is recommended as the structural material; however any of the metals commonly used in engine block construction may be employed for this purpose. The cylinders are closed at their outer ends by heads 15, 16 and 17 respectively, which may be removably secured to the cylinders by means such as cap screws 18, or may be formed integral with the cylinders.

Arranged to reciprocate within the cylinders are pistons 21, 22 and 23, which are removably attached by conventional means such as wrist pins 24, 25 and 26 to piston rods 27, 28 and 29. These piston rods are removably.

connected to a common crankpin 31 and operate through the crankpin 31 and crank webs 32 to translate the reciprocating motion of the pistons into rotary motion of the centrally located crank shaft 33.

In the preferred embodiment of the invention the centers of the cylinders do not lie in a plane. As shown in FIGURES l, 3 and 7, the cylinders are offset along the major axis of the crank shaft so that their centers coincide with the centers of their respective piston rods.

One end of the motor block 14 is closed by means of a removable cover plate 34 provided internally with a bearing 35 for one end of the crank shaft 33. The opposite end of the motor block is closed by means of a removable cover plate" 35 having bearing means 36 through which the extension of crank shaft 33 is journaled to provide an external drive shaft 37.

Removable plugs 38 in ports 39 in the sides of motor block 14 provide means for adding and draining crankcase lubricant and allow easy access to the crankcase for inspection and servicing of the motor components.

In the preferred form of the invention a cylindrical cavity 41 cast within the motor block 14 concentric with the crankshaft 33 is adapted to accommodate valve means for controlling the flow of fluid through the motor. The Walls of the cavity provide a casing for the fluid distributing valve, and ports 42 and 4-3 in the opposite sides of the cavity and near its opposite ends communicate with external fittings 46 and'47, respectively, through passages 44 and 45 (partially shown in FIGURES 4, and 6), respectively.

As shown schematically in FIGURE 1, the two external fittings 46 and 47 are connected by conventional conduit means with a suitable source of fluid under pressure 51, such as a conventional hydraulic pump, and with fluid reservoir 52, which is connected to the intake side of said fluid pressure source 51. In the preferred embodiment commonly available adjustable and reversible valve means (shown schematically in FIGURE 1) 53 are provided in the fluid conduits between external fittings 46 and 47, fluid reservoir 52 and pressure source 51 for controlling the rate of flow of fluid to the motor and permitting the direction of flow between valve 53 and the fittings 46 and 47 to be reversed readily.

As shown in FIGURE 2, passages 54, 55 andso within motor block 14 communicate between ports 57, 58 and 59 in the walls of the cavity 41 and ports 61, 62 and 63 in the work chambers of cylinders 11, 12 and 13, respectively, providing'ducts for the flow of fluid under pressure from the cavity to each of the cylinders during its intake cycle and from each cylinder back into the cavity during its exhaust cycle.

Examination of the basic theory and operation of the rotary distribution valve of the invention will disclose a number of alternative arrangements by which the principles involved may be practiced. FIGURE 3 will show clearly the simplest form of the Valve and will illustrate to one skilled in the art many of the inherent advantages which make it the preferred construction. In this embodiment of the invention, the cylindrical valve body is formed concentric and intergal with the crankshaft 33 where it passes through the cavity 41. The valve body is of substantially the same diameter as cavity 41 so that the walls of the valve body and the cavity are in fluid tight relation, and suitable packing or seals 81 near the opposite ends of the cavity eliminate any possibility of fluid leakage therefrom. Annular grooves 71 and 72 are formed in the valve body near its opposite ends to register with ports 42 and-43, respectively, and grooves 73 and 74 are formed in opposite sides of the valve body near its center to register in turn with ports '57, 58 and 59. Groove 74 communicates with annular groove 71 by way of longitudinal slot 75in one side of the valve body, and groove 73 communicates with annular groove 72 by way of longitudinal slot 76 in the side of the valve body opposite slot'75.

The operation of the fluid motor may easily be followed by reference to the foregoing description and the accompanying drawings. For illustrative purposes the specific mode of operation will be traced first with the external drive shaft 37 rotating in the direction indicated by the arrows on crankshaft 33- in FIGURES 5 and 6. Assuming that the motor has come to rest in the position shown in FIGURE 2, piston 21 has completed its exhaust stroke and is ready to begin its work stroke, piston 22 has passed the mid-point in its exhaust stroke, and piston 23 has not yet reached the mid-point in its work stroke.

To actuate the fluid motor, valve 53 is opened to permit fluid under pressure to flow from pressure source 51 through external fitting 46, passage 44 and port 42 into annular groove 71 of the rotary distributing valve. FIGURES 4, 5 and 6 depict in detail the flow of fluid to and from the rotary distributor valve and within the valve itself at this time.

As shown in those figures, the fluid passes from groove 71 into groove 74 by way of longitudinal slot 75. Groove 74 is in communication with ports 57 and 59, and the pressure fluid passes through them into passages 54 and 56 and thence by way of ports 61 and 63 into the work chambers of cylinders 11 and 13, respectively.

The fluid pressure acting on pistons 21 and 23 drives them inward to complete their work strokes, thereby imparting rotary motion to the crankshaft 33 and external drive shaft 37 through the cooperation of piston rods 27 and 29, crankpin 31, crank webs 32.

The rotary motion thus imparted to the crank and the crankshaft by pistons 21 and 23 operates through piston rod 28 to force piston 22 in cylinder 12 outward to complete its exhaust stroke. During this stroke the pressure fluid in the work chamber of cylinder 12 is discharged from the chamber through port 62 and passage 55.

Groove 72 in the fluid distributing valve is in communication with passage 55 through port 58, and the fluid exhausted from cylinder 12 flows into this groove and then, by way of longitudinal slot 76, annular groove 72, port 43, passage 4-5, external fitting 47 and the external duct system, to the intake side of valve 53. Valve 53 directs the flow of this fluid to fluid reservoir 52, where it is ready to be recirculated through the motor by pressure source 51.

The arc length of groove 74- is such that at the same moment piston 23 reaches its inwardmost position at the end of its work stroke the communication between passage 56 and groove 74 is broken, and the valve body covers and seals port 59, thus cutting ofl the flow of pressure fluid to the work chamber of cylinder 13. Since piston 23 remains substantially at rest while crank pin 31 rotating about crankshaft 33 moves through the center line of cylinder 13 and begins the outward motion associated with the exhaust stroke of piston 23, the pressure of the fluid trapped within the work chamber has no eflect on the operation of the motor. During this brief rest period for piston 23, the rotation of crankshaft 33 brings groove 73 into registration with port 59, so that when piston 23 begins its outward or exhaust stroke the work chamber of cylinder 13 is in communication with external fitting 47 through passage 56, port 59, groove 73, slot 76 annular groove 72, port 43 and passage 45. External fitting 47 is connected with the intake side of valve 53 and through it with fluid reservoir 52. By means of this arrangement, the fluid exhausted from the work chamber by the outward movement of the piston is returned to the reservoir where it is ready for re-circulation to the motor by pressure source 51.

In similar fashion, when piston 21 reaches the end of its work stroke, the rotating valve body shuts ofi the flow of pressure fluid to the work chamber of cylinder 11 and closes port 57 until, simultaneously with the commencement of the exhaust stroke of piston 21, the port is reopened, now in communication with groove 73 and the outlet means leading from it to valve 53 and fluid reservoir 52.

When piston 22 concludes its exhaust stroke near the head of cylinder 12, the rotary valve of the invention brings the work chamber of cylinder 12 in communication with groove 74 and the duct system connecting it with fluid pressure source 51.

As will be clear at this point in the description, the steps just outlined are precisely the same for the intake and exhaust strokes of each of the pistons. While the motor is rotating in the direction shown, groove 74 and its associated slot *75 and annular groove 71 serve as the intake means of the rotary valve, and groove 73, slot 72 and groove 76 comprise the exhaust means. This novel arrangement provides the fluid motor of this invention with many inherent advantages not found in most of the existing reciprocating fluid motors. One such advantage stems from the fact that a constant flow of pressure fluid is maintained in the rotary valve during all phases of operation of the motor. This feature eliminates completely the inefficiencies associated with the interruption, pulsation and reversal of flo-w of the pressure fluid occurring in the various valve systems employed in many of the existing devices. Also, the rotary valve as shown avoids the need for complex cross-feed ducting and the attendant possibility of failure of the plurality of conduits and fluid seals involved therein. The strength and simplicity of design of the valve reduces still further the chance of motor failure and the need for costly repairs.

As illustrated herein, the arrangement of the rotary valve as an integral part of the crankshaft insures the un varying accuracy of the timing of all phases of operation.

The speed of the motor is readily and precisely controlled by adjustment of the flow of pressure fluid through valve 53, and in operation all changes of speed are accomplished smoothly and positively.

Conventional braking means external to the motor may be employed for use of the motor in connection with any form of vehicle, tool or appliance, but such means are not required. The rotary valve itself provides an effective braking device for the motor. Whether used with an external brake or not the motor can be stopped as quickly as desired by merely reversing the flow of pressure fluid to the rotary valve by means of valve 53.

When valve 53 is reversed so that pressure source 51 is connected with groove 73 of the rotary valve, the direction of flow of the pressure fluid through the motor is reversed, and the pressure fluid acting against the moving pistons furnishes a sure, direct and powerful braking force.

Conventional means are provided in valve 53 permitting the pressure source to remain in operation even when valve 53 is fully closed. This allows the motor to remain at rest and yet be ready at all times to be started without delay.

The preferred embodiment of the motor as depicted in these pages can be operated as efficiently and conveniently in one direction as in the other. When valve 53 is adjusted to direct pressure fluid to groove 73, the mode of operation is exactly the reverse of that described herein above wherein groove 74 is on the intake side of the rotary valve. Under such circumstances self-braking is accomplished in precisely the manner detailed above, but with the direction of fluid flow reversed at all stages.

As shown earlier, the present invention is susceptible of any number of variations. The rotary valve may be constructed as a unit separate and removed from the crankshaft and may be linked with the crankshaft by any convenient gear, chain, belt, electrical or fluid-operated means. Valve 53 may be made a part of the motor assembly itself. It may for example be formed integral with the rotary valve. These are but two of forms contemplated by the invention, but they demonstrate the fact that the present disclosure is merely illustrative of the claims made herein.

In particular, what is claimed is:

1. A reciprocating piston driven fluid pressure operated motor, comprising a plurality of cylinders each having a work chamber, a piston member reciprocable therein, and a passage for conducting pressure fluid to said work chamber during the work stroke of its piston member and from said Work chamber during the exhaust stroke of said piston member, a rotatably mounted drive shaft, motion transmitting means operatively connecting each piston member to said drive shaft, an external source of fluid under pressure, an external outlet for discharged fluid, a cylindrical valve casing surrounding a segment of said drive shaft and forming a fluid-tight connection with the outer surface thereof, ports in said casing near its opposite ends communicating with said external source of fluid under pressure and said external outlet, respectively, annular grooves formed on the drive shaft each registering with one of said ports, grooves formed on the opposite sides of the drive shaft between said annular grooves to provide intake and exhaust vessels, longitudinal slots formed on the opposite sides of said drive shaft connecting one of said vessels with one of said annular grooves and the other vessel with the second annular groove, and ports in said valve casing communicating with said fluid conducting passages, upon rotation of said drive shaft, said vessels alternately connecting said fluid conducting passages with said source of fluid under pressure and said external outlet through said longitudinal slots and annular grooves.

2. A reciprocating piston driven fluid pressure operated motor, comprising a plurality of cylinders radially disposed about a crankcase each having a work chamber, a piston member reciprocable therein, and a passage for conducting pressure fluid to said work chamber during the work stroke of its piston member and from said work chamber during the exhaust stroke of said piston member, a drive shaft rotatably mounted in said crankcase, motion transmitting means operatively connecting each piston member to said drive shaft, an external source of fluid under pressure, an external outlet for discharged fluid, a cylindrical cavity within said crankcase with its Walls forming a valve casing surrounding a seg ment of said drive shaft and in fluid-tight connection with the outer surface thereof, ports in said casing near its opposite ends communicating with said external source of fluid under pressure and said external outlet, respectively, annular grooves formed on the drive shaft each registering with one of said ports, grooves formed on the opposite sides of the drive shaft between said annular grooves to provide intake and exhaust vessels, longitudinal slots formed on the opposite sides of said drive shaft connecting one of said vessels with one of said annular grooves and the other vessel with the second annular groove, and ports in said valve casing commum'oating with said fluid conducting passages, upon rotation of said drive shaft, said vessels alternately connecting said fluid conducting passages with said source of fluid under pressure and said external outlet through said longitudinal slots and annular grooves.

3. A reciprocating piston driven pressure fluid operated motor, as claimed in claim 2, wherein motion transmitting means operatively connecting each piston member to said drive shaft comprises a piston rod attached at one end to said piston member and at its opposite end to a common crankpin, said crankpin being connected to crank webs attached to said drive shaft.

4. In combination with a reciprocating piston driven pressure fluid operated motor as claimed in claim 3, means for effecting reversal of the direction of rotation of said motor by directing the flow of pressure fluid from said external source of fluid under pressure through the port in said valve casing which formerly communicated with said external outlet and connecting the port in said valve casing which formerly communicated with said source of fluid under pressure with said external outlet.

5. A reversible fluid pressure operated motor, comprising three cylinders radially disposed about a common crankcase each having a working chamber, a piston member reciprocable therein, and a passage for conducting pressure fluid to said work chamber during the Work stroke of its piston member and from said Work chamber during the exhaust stroke of said piston member, a drive shaft rotatably mounted in said crankcase, motion transmitting means operatively connecting each piston member tosaid drive shaft, an external source of fluid under pressure, an external outlet for discharged fluid, a cylindrical cavity Within said crankcase with its Walls forming a valve casing surrounding a segment of said drive shaft and in fluid-tight connection with the outer surface thereof, ports in said casing near its opposite ends communicating with said external source of fluid under pressure and said external outlet, respectively, annular grooves formed on the drive shaft each registering with one of said ports, grooves formed on the opposite sides of the drive shaft between said annular grooves to provide intake and exhaust vessels, longitudinal slots formed on the opposite sides of said drive shaft connecting one of said vessels with one of said annular grooves and the other vessel with the second annular groove, ports in said valve casing communicating with said fluid conducting passages, upon rotation of said drive shaft, said vessels alternately connecting said fluid conducting passages with said source of fluid under pressure and said external outlet through said longitudinal slots and annular grooves, and means for connecting said ports in said valve casing alternately with said source of fluid 8 under pressure and said external outlet to reverse the direction of rotation of said motor.

6. A reversible fluid pressure operated motor as claimed in claim 5, wherein said motion transmitting means operatively connecting each piston member to said drive shaft comprises a piston rod attached at one end to said piston member and at its opposite end to a common crankpin, said crankpin being connected to crank Webs attached to said drive shaft, and said cylinders are offset longitudinally of said crankshaft so that their centers coincide with the centers of their respective piston rods.

References Cited in the file of this patent UNITED STATES PATENTS 674,237 Gibson May 14, 1901 736,438 Philips Aug. 18, 1903 2,372,523 Sinclair Mar. 27, 1945 2,397,130 Dawson Mar. 26, 1946 2,861,552 Creighton et a1. Nov. 25, 1958 2,984,223 Budzich May 16, 1961 

1. A RECIPROCATING PISTON DRIVEN FLUID PRESSURE OPERATED MOTOR, COMPRISING A PLURALITY OF CYLINDERS EACH HAVING A WORK CHAMBER, A PISTON MEMBER RECIPROCABLE THEREIN, AND A PASSAGE FOR CONDUCTING PRESSURE FLUID TO SAID WORK CHAMBER DURING THE WORK STROKE OF ITS PISTON MEMBER AND FROM SAID WORK CHAMBER DURING THE EXHAUST STROKE OF SAID PISTON MEMBER, A ROTATABLY MOUNTED DRIVE SHAFT, MOTION TRANSMITTING MEANS OPERATIVELY CONNECTING EACH PISTON MEMBER TO SAID DRIVE SHAFT, AN EXTERNAL SOURCE OF FLUID UNDER PRESSURE, AN EXTERNAL OUTLET FOR DISCHARGED FLUID, A CYLINDRICAL VALVE CASING SURROUNDING A SEGMENT OF SAID DRIVE SHAFT AND FORMING A FLUID-TIGHT CONNECTION WITH THE OUTER SURFACE THEREOF, PORTS IN SAID CASING NEAR ITS OPPOSITE ENDS COMMUNICATING WITH SAID EXTERNAL SOURCE OF FLUID UNDER PRESSURE AND SAID EXTERNAL OUTLET, RESPECTIVELY, ANNULAR GROOVES FORMED ON THE DRIVE SHAFT EACH REGISTERING WITH ONE OF SAID PORTS, GROOVES FORMED ON THE OPPOSITE SIDE OF THE DRIVE SHAFT BETWEEN SAID ANNULAR GROOVES TO PROVIDE INTAKE AND EXHAUST VES- 